Thanks again everyone.
Sexing umbees can be tough. Partly due to the fact females can have great colors too. Also, some have said due to agression, males have been known to keep subdominant colors, even mimicking the female pattern.
What I did was take away the dominants while the juvenile umbees were growing out. It turned out my male was the second to the bottom of the pecking order out of his five siblings!! The females grew much faster the first 3 or 4 months.
I was lucky and knew the sex around 3.5" TL. Here are some shots to compare to his female sibling when they were around 3-4" (with him being the dominant):
male on top:
male on left
And here he was the other day yawning, enjoy: